Process for manufacturing hard objects in silicidized carbon or other similar substances



Nov. 27, 1934. A. L. MINGARD 1,982

PROCESS FOR MANUFACTURING 'HARD OBJECTS IN SILICIDIZED CARBON OR OTHERSIMILAR SUBSTANCES Filed April 20, 1932' A VJ...,

Patented Nov. 27, 1934 1,982,012 rnocnss ron MANUFACTURING mum OBJECTSIN SILICIDIZED CARBON OTHER SIMILAR SUBSTANCES Aurele Louis Mingard,Lausanne, Switzerland Application April 20, 1932, Serial No. 606,490 InFrance May 11, 1931 lclaim.

The object of this invention is a process for manufacturing very hardobjects, particularly grinding stones, in silicidized carbon or othervery hard materials.

i The process consists essentially in transforming objects of any shape,made of carbon, into another very hard substance particularly intosilicidized carbon, without altering their shape and by chemicalreaction at high temperature.

I The crucible in which the reactions take place is filled with amixture of substances capable of reacting upon each other at thetemperature produced by an electric arc struck between electrodes. Bythe influence of this are and as a result of the 5 chemical reactionsbetween the substances forming the charge, metallic vapors are produced,

which reach a certain pressure, forming a pocket with the are in thecenter, and which pocket gradually increases in volume until the objectsto be transformed, and which at the commencement of the operation wereembedded in the charge, are enclosed within the pocket charged withmetallic vapors, without having changed their position, and aresubjected to the action of these vapors, until the transformation into avery hard material particularly silicidized carbon, is completed.

The transformation is preferably produced in a furnace consisting of acrucible l of any desired ,0 shape, containing a lining of refractorybricks.

This furnace is placed either vertically or horizontally and may be ofthe tilting type. It is provided with electrodes 2 of carbon or othermaterial capable of resisting high temperatures. l6 These electrodes maybe placed into the furnace in any position with respect to the furnace,and at any variable position with regard to each other. They can, forinstance, be placed along the center line of the furnace in line witheach other and L0 at any distance from each other. Each electrode isfitted on the end inside the furnace with a piece of carbon 3 of anysuitable shape, cylindrical, coneshaped etc. The object or objects ofcarbon 4 to be transformed are attached to the electrodes [5 in anysuitable manner, along their center line for instance if they arecylindrical. The other electrode may also be provided with a similarobject or an object of different shape to the one attached to the firstelectrode. so In the case of a body of carbon in the form of a grindingwheel, the body may be mounted on the electrode by means of the axialbore formed therein. When so mounted the body is held in place on theelectrode by friction between the i5 bore in the body and the electrode.

.bon, into silicidized carbon or other material proceeds in thefollowing manner.

The furnace is charged with a mixture of sub-' stances capable ofproducing by chemical reaction at high temperature the transformation ofthe objects of carbon into silicidized carbon or other very hardsubstances.

As an example of such substances forming the charge the followingmixture is mentioned:

For obtaining silicidized carbon:

' Parts Silica I 30 Carb l the charge in the furnace, liberating fromone of the constituents silicon vapors, or other vapors according to thenature of the charge.

This reaction may be represented as follows:

These vapors reach a certain pressure and rapidly form around the are apocket 5 with the arc in the center. The pocket gradually increases involume until the objects of carbon which it.

is desired to transform are enclosed within this pocket. These objectsare then subjected to the action of. metallicfvapors of silicon or otherelements and are transformed into silicidized carbon or as the case maybe into other very hard materials with carbon as a base, withoutchanging in shape or position in the furnace and without passing throughany other physical changes. The objects may then be removed from thefurnace'and the operation can be repeated.

I claim:

A method of producing grinding wheels comprising positioning a wheelformed 01' carbon on one of a pair of electrodes, surrounding the elec-5 trodes and carbon wheel with a charge of silica and carbon,electrically energizing the electrodes and striking an are between them,maintaining the vapor phase products of conversion formed

